Chapter 5: AD12-8 Driver Reference
Manual Number: 00650-014-4
Page 5-1
Chapter 5: AD12-8 Driver Reference
This chapter provides detailed information on the functions available from the AD12-8 driver. The
chapter is divided into four sections, first is a section detailing the use of this driver, second is a task
summary, third is the task reference and last is an error code summary.
Using the Driver
The Point List Concept
Most functions of this driver work with a point list. The point list is a list of point addresses in the
order that you desire to have conversions performed. A point address is a number specifying the
channel of the AD12-8 and the AT16-P. The first 16 point addresses (0-15) refer to the AT16-P
channels for the AT16-P attached to channel 0 of the AD12-8. The second 16 point addresses (16-
31) refer to the 16 channels of the AT16-P attached to channel 1 of the AD12-8, and so on. Thus,
with eight single ended A/D channels, a point address may be as large as 127.
If your are using LVDT8-Ps, then the first eight point address (0-7) refer to the LVDT8-P attached
to channel 0 of the AD12-8. The second eight point addresses are not used (8-15). Thus with eight
single-ended A/D channels, a point address may still be as large as 127, but there would only be a
maximum of 64 LVDT8-P channels.
You may install point addresses into the point list in any order, or with multiple entries for the same
point address. For example the order could be 15-12-12-11-9-127-1-1-0 etc. The order that point
addresses are installed in the point list is the order in which you call the driver to install them. Each
new entry is appended to the end of the list.
A point list index is used by the driver to keep track of which point address is the next to be
converted. After each conversion the index is incremented to the next position in the list. When
the index reaches the end of the list it is automatically reset to the start of the list. If you desire to
set the list index to the start of the list at any time, you may use TASK 11.
The point list is dynamic. During program operation, if you desire to clear the point list and add a
different set of points, this is done quite easily using the tasks provided.
The main advantages of a point list are that conversions can be done in any order and the driver
takes care of setting the AT16-P and/or LVDT8-P channel and the AD12-8 channel, as well as
gains, linearization and scaling.
Other Software Features
The driver provides the ability to use the programmable gain feature of the AT16-P. You may
assign gains to a given point address directly. Each point address may have its own gain code
associated with it. This is useful when differing input ranges are desired using the same AT16-P.
The driver also provides the ability to make a function assignment to each individual point address.
You may assign a thermocouple curve or a scaling range to a point address. Look up tables are
contained in the driver to convert counts to the proper temperature. Reference junction compensa-
tion may also be performed.
